Paul di Resta admits it will be hard to catch Sauber in the fight for sixth place in the constructors' championship with just two races remaining.

His Force India team lies seventh in the standings, 29 points behind Sauber and 22 points ahead of Williams as the grand prix circus moves on to Austin for the first time.

"I think under normal circumstances you'd probably say Sauber are out of reach. Williams looked good in Abu Dhabi, but I think we're in a strong enough position to defend from them," said Di Resta. "Austin will be an unknown but it's a new track so it's likely to be similar to Abu Dhabi with new tarmac and a smooth surface. So there's every reason to believe we can be competitive there."

With no prior experience of driving on the Circuit of the Americas, most drivers have been familiarising themselves with the vagaries of the track on simulators.

"I've not done a massive amount, to be honest. I've seen some maps of the circuit, but the main preparation will come from my simulator session on the Monday of race week. So I'll arrive in America with it fresh in my mind."